Prosthetic limb having an elastic covering



Sept. 10, 1968 R. v. GARCIA PROSTHETIC LIMB HAVING AN ELASTIC COVERING 4 Sheets-Sheet 1 Filed Oct. 23, 1964 Sept. 10, 1968 R. v. GARCIA PROSTHET'IC LIME HAVING AN ELASTIC COVERING 4 Sheets-Sheet 2 Filed Oct. 23,

Sept. 10, 1968 R. v. GARCIA 3,400,408

PROSTHETIC LIMB HAVING AN ELASTIC COVERING Filed Oct. 23, 1964 4 Sheets-Sheet .2

FIG. 5

FIG. 7

Sept. 10, 1968 R. v. GARCIA PROSTHETIC LIME HAVING AN ELASTIC COVERING Sheets-Sheet Filed 001.. 23, 1964 a5-; F E. I 30- l ll-L. 1" Jr United States Patent ABSTRACT OF THE DISCLOSURE A prosthetic device in which a skeletal structure includes an articulated joint enabling the structure to be pivotally moved between extended and collapsed positions, and an elastic cover surrounding and accommodating the skeletal structure and exerting resilient force on the structure to urge the same towards its exended position.

This invention relates to prosthetic devices and more particularly to an artificial limb which is adapted for replacing the limb of an amputee.

It is an object of the invention to solve the psychological and fabrication problems associated with such de vices. These problems arise since the presently available devices lack flexibility and a natural appearance. Such devices have an adverse psychological effect on those who wear them after having an amputation.

Most of the prosthetic devices used at present are composed of rigid material such as rigid plastics, wood, aluminum or the like. By the use of these materials, it is not possible to obtain the desired flexibility, the desired elasticity of movement nor the desired esthetic appearance of the prosthetic device.

Therefore, another object of the present invention is to provide a replacement for an amputated limb which both reliably operates to give to the person a natural appearance and hide at least partially his defect.

A further problem which must be solved by prosthetic devices is that of providing a feeling simulating that of a normal member when touched. In devices presently employed, the prosthesis is constructed of rigid material which immediately betrays its artificiality when touched. Accordingly, it is another object of the invention to provide a prosthetic device having a life-like fee].

In known prosthetic devices, there is provided a mechanism to enable the device to undergo varying degrees of movement. Such mechanisms usually extend to the exterior of the prosthetic device and contact any covering clothing. Frequently, this involves staining of the clothing from lubrication and the like of the mechanism.

A feature of the prosthetic device, according to the invention, is that it includes a flexible covering encasing the working mechanisms to thereby provide a pleasing appearance for the prosthetic device and eliminate the possibility of lubrication stains or the like on covering articles of clothing.

A still further object of the invention is to provide an artificial limb which anatomically resembles the limb which it replaces in external appearance, in consistency to the feel, in color and in operation. In this regard, it is a feature of the invention that the internal skeletal structure simulates that of the skeletal structure of the limb being replaced, while the exterior of the prosthesis visually and physically resembles the human limb.

3,400,408 Patented Sept. 10, 1968 In accordance with the invention, there is provided a skeletal structure which has a degree of freedom of movement corresponding to that of the skeletal structure of the limb which the device is intended to replace. Surrounding the skeletal structure is an elastic cover which encases the skeletal structure and exerts resilient force thereon to urge the skeletal structure to an initial position corresponding to the natural relaxed position of the limb. Thus, when the prosthetic device is moved from such initial position the elastic cover tends to return the device to its initial position.

In the particular case where the prosthetic device is an artificial leg, there is provided in the skeletal structure an articulated joint corresponding to the knee joint which is left freely rotatable. The elastic cover urges the skeletal structure to a position corresponding to an extended position of the leg. During walking, the knee joint is rotated and the elastic cover and skeletal structure cooperate to support the weight of the person using the artificial leg. This is the situation when the artificial leg is placed forwardly and the weight of the person is applied thereto in the forward step during walking. As the person bears down on the artificial leg and continues forward movement, this skeletal structure and elastic cover cooperative- 1y support the weight of the person while the knee joint undergoes gradual rotation from a bent position of the leg to an extended position. The return of the leg to its extended position is achieved by the elastic restoring force developed by the elastic cover. By reason of the above, the person using such artificial limb will have natural walking movement. This is particularly manifested by the provision of the freely rotatable knee joint.

In the event, however, that the person utilizing the artificial leg desires to remain standing, sitting or to assume a squatting position for an extended length of time, it may be desirable to lock the leg in such position so as to relieve the person from applying force via the stump of the amputated member to the prosthetic device in order to maintain the same in such position against the action of the elastic cover. Therefore it is another object of the invention to provide means for selectively locking the prosthetic device in a plurality of positions corresponding to sitting, standing and squatting positions.

It is a significant feature of the invention to employ an elastic cover in conjunction with a skeletal structure which has degrees of freedom simulating that of the Skeletal structure of the normal limb which the device is to replace. Such elastic cover may be constituted of a mass of polyurethane foam, foam rubber or the like. The density and resiliency of the mass constituting the elastic cover is such that life-like feel is provided While structural requirements are met.

A further advantage of the device according to the invention is its simple mechanism and its light weight as a result of the elastic cover, the weight being about half the weight of conventional prosthetic devices.

Another advantage of the device according to the invention is that the cost of manufacture is substantially reduced because of its simplicity and the high production that may be obtained with a minimum of personnel.

As a further feature of the invention, there may be employed a thin cover on the elastic cover which confers a water-proofing to the prosthetic device while simulating the natural color of the persons skin.

Numerous further objects, advantages and features of the invention will become apparent from a consideration of the embodiments as shown in the attached drawing wherein:

FIGURE 1 is a perspective view of an artificial leg according to the invention;

FIGURE 2 is an elevational view of the leg with the outer covering broken away to show the internal leg structure;

FIGURE 3 is an exploded view of the internal leg structure shown partly in section;

FIGURE 3a is a sectional view taken along line IIIIII of FIG. 3;

FIGURE 4 is a sectional view of the lower portion of the leg structure showing the details of construction of the ankle joint;

FIGURE 5 is a sectional view taken along the line VV of FIG. 4;

FIGURE 6 is a sectional view taken along line VIVI in FIG. 2 and showing details of construction of the knee joint;

FIGURE 7 is an end view of a sub-assembly of the knee joint;

FIGURE 8 is a side view of the knee joint with one of the elements of the sub-assembly removed for purposes of illustration;

FIGURE 9 is a sectional view taken through the upper portion of the artificial leg showing a control device; and

FIGURE 10 shows the leg structure supported in a mold and adapted for being covered.

In FIGURE 1 of the drawing there can be seen the artificial leg according to the invention as it will appear when viewed. The leg is constituted of an internal structural arrangement 2 simulating the skeletal structure of a human leg. The structure 2 is encased in a mass of foam material 3 which in turn is covered with a latex outer layer 4. The outer contour of the leg 1 is smooth and uninterrupted. By virtue of the use of the foam material 3, the outer surface of the leg may conform with as much detail as desired as regards the shape and configuration of a normal leg.

The structural arrangement comprises an elongate footplate 5 having a lower concave surface 6. The footplate is anatomically equivalent to a normal foot in that the rear portion 8 corresponds to the calcaneum while the central arch portion 9, with the concave surface 6, simulates the tarsus of the foot. The front portion 10 corresponds to the metatarsum support. The footplate is essentially constituted by a flat portion 11 at the base of the element and an upstanding circular portion 12 at the rear of the plate.

A web 13 constitutes a reinforcement for the plate. In the portion 12 there is provided an upwardly facing opening 14 having a threaded surface 15. Anatomically the portion 12 corresponds to the subastragaline articulation (without movements).

A cup member is threadably engaged in the opening 14 in the footplate 5'. The cup member is provided with a smooth upwardly facing hemispherical concavity 21. An end portion 22 of the cup member is provided with threading. The member 20 corresponds anatomically to the astragal.

A cap member has a threaded portion 31 threadably engaging portion 22 of cup member 20. The cap member 30 has an oval shaped hole 32 provided therein. The oval hole has its greatest dimension arranged in a front-to-rear direction.

A rod assembly is provided including a rod member 41 and a tube member 46. The rod member 41 includes a spherical portion 42 at one end and a threaded portion 43. The spherical portion 42 is accommodated in the concavity 21 for free movement therein. The rod member 41 extends through the oval hole 32 in the cap member 30 which thereby limits the degree of movement of rod member 41 as shown in P16, 4 in dotted outline. As a consequence of the elongated arrangement of the hole 32, the rod will have greater movement in the front and rear direction as compared to lateral movement. Consequently, the movement of flexibility in extension will be of larger magnitude than that of supination. Anatomically, the movement of the member 41 within the oval hole 32 corresponds to the articular capsule and the small ligaments of the tibia astragal articulation. The foam mass 3 encircling the skeletal structure 2 applies resilient force to hold the rod member 41 centrally in the opening 32, and relative movement of the rod member 41 within opening 32 will take place only when external force is applied such as when force is exerted on the foot.

The threaded portion 43 of member 41 is threadably engaged in portion 44 of tube 42.

It is seen therefore that the rod assembly may undergo limited movement with respect to the cup member 20 secured in the elongate footplate. The rod member 41 anatomically corresponds to the distal epiphisis of the tibia and the malleolus of the perone, while in combination with the cup member 20 and the cap member 30 from the tibia astragal articulation as noted above.

The tube 46 has an internally threaded portion 45 which is adapted for engaging a sub-assembly of a portion of the knee joint. Anatomically tube 46 corresponds to the diaphysis of the tibia. The tube 46 may be adjusted as regards the depth of engagement both of member 41 and sub-assembly 60 to provide adjustment of the length of the engaged portion of tube 46 to correspond to the height of the person employing the prosthesis.

The knee joint comprises sub-assembly 60 composed of symmetrical elements 61 and 62 joined along mating surfaces, and T-shaped member 64. The elements 61, 62 are secured together by fasteners extending through bores 63. The T-shaped member 64 includes a cylindrical portion 65 and an upwardly projecting portion 66.

The members 61 and 62 cooperatively define a threaded end portion 67 which is threadably engaged in end portion 45 of tube 46. The elements 61, 62 are formed with respective lugs 68, 69. The lugs are provided with aligned openings 70, 71. The cylindrical portion 65 of T-shaped member 64 is supported in the openings 70 and 71 for rotation. The upwardly projecting portion 64 extends in the space between the lugs 68, 69 of the sub-assembly 60. The symmetrical elements in the space between the lugs include surfaces 72, 73 (FIG. 8) which constitute end abutment surfaces for the upwardly projecting portion 66 of the T-shaped member 64. Thereby the member 64 and the sub-assembly 60 are freely rotatable about an axis passing centrally through the cylindrical portion 65 between limit positions established by surfaces 72, 73. The range of movement provided by surfaces 72 and 73 for the knee joint corresponds to the range of movement of the knee joint in a human leg.

The elements 61 and 62 are provided with cavities 74 and 75 (FIG. 7). Supported within the cavities is a sector element 76 having a plurality of openings 77. The sector element 76 is supported within the cavities 74, 75 means of fasteners passing through bores 63 such that the openings 77 open into the space between the lugs 68 and 69 of the sub-assembly 60.

Within the T-shaped member 64 is an axially extending bore 80. Contained within the bore is a slidable retractable pin 81. Within the bore there is secured a ring 82 having a central opening in which a stem 83 of the pin 81 is slidably supported. A spring 84 is supported be-- tween the ring and the end of the pin 81 tending to urge the pin outwardly beyond the contour of cylindrical portion 65. A cable 85 is connected to the end of stem 83 and extends through an opening 86 in the leg externally thereof. A ring 87 is attached to the end of the cable and permits the user to retract or extend the pin as desired. For prolonged retraction a stud 88 is provided on which the ring 87 may be supported. Thus, if the knee joint is to be in a freely rotatable state, the ring 87 is engaged and supported on the stud 88 whereby the pin 81 will be retracted into the bore 80 of T member 64. This will be the normal arrangement of the leg. If the knee joint is to be locked as for example during prolonged standing, sitting or squatting, the ring 87 will be disengaged from the stud 88 and the pin 81 will be extended under the action of spring 84 and engaged in one of the openings 77 of the sector element 76. The locking of the knee joint is not absolutely necessary and the knee joint may always remain unlocked without causing undue discomfort for the user. In such case sector element 76 and the actuating assembly constituted by pin 81 and cable 85 may be omitted. In such arrangement, the outer surface of the leg will dispense with the opening 86 and the stud 88 and thereby be completely smooth.

When the stud and actuating assembly are provided, this is utilized to lock the knee joint in one of a plurality of positions as defined by the particular openings 77. Thus, for example, if the person using the leg is to be standing for a long period of time then the pin will be engaged in the opening which will form a locked 180 angle between portion 66 and tube 46. This corresponds to an extended position of the leg. If the person using the leg desires to sit and lock the leg for such a position, then the pin will be engaged in the hole which will form a 90 angle between the portion 66 and the tube 46. For squatting positions, and the like, a third opening 77 is provided which fixes the angle between the portion 66 and the tube 42 at 135.

It is understood that a greater number of positions may be provided, if desired, corresponding to the particular demands established by the user. In this regard it is of advantage that such positions can be provided for any leg merely by varying the locations of the holes 77 in the sector element 7 6.

Under general conditions of walking, however, it is contemplated that the knee joint will be unlocked and free for rotation. As the leg is extended during a forward step, the knee joint will undergo rotation as the weight of the user is applied to the forwardly extended leg. Stability is achieved by the surrounding mass of foam material which serves the function of normal muscular tissue. Thus, stability is obtained with the knee joint unlocked even during bent positions of the leg. As the person advances forwardly the leg will tend to straighten under the action of the resilient force exerted against the skeletal structure by the surrounding foam material. In this respect it is to be noted that the skeletal structure is embedded in the foam material such that the foam material tends to maintain the skeletal structure in an extended or straight position.

The sub-assembly 60 and the T-shaped member 64 anatomically correspond to the femoral condyles and superior apiphysis of the tibia and ligaments. The foam material corresponds to a muscular mass and mechanically substitutes the function of extension of the quadriceps.

The portion 66 has an upper threaded end which is threadably engaged in a tubular member 89 which has respective opposite threaded ends. The member 89 is threadably engaged with a member 90 which is secured by fasteners 91 to a container 92. The depth of threaded engagement of member 64 and member 90 in tubular member 89 can be varied for adjustment of the distance between the knee joint and the container. The member 90 has a central opening 93 which accommodates passage of the cable 85. The container 92 serves the purpose of securely engaging the stump of the amputee.

The manufacture of the artificial leg is extremely simplified in that the entire skeletal structure may be preassembled. In order to fit an amputee for a prosthesis, measurements are taken of the stump of the amputee. Thereafter the measurements of the existing member are taken by forming a plastic mold around the existing member and the mold dimensions are then reversed left to right and a further mold is cast. Such a mold is of the general type shown by mold in FIG. 10. Preferably the mold is constituted of aluminum. Internally the mold corresponds to the outside shape of the leg. The preassembled skeletal structure is placed within the mold and thereafter the mold is filled with the foam material so that the skeletal structure is encased within the foam and the surface of the foam corresponds to the desired surface of the member. Thereafter the skeletal structure with the foam thereon is removed from the mold and the thin covering 3 such as latex or the like is placed over the foam material. The latex is of a color simulating that of human skin.

The density of the foam material is such that it corresponds approximately to the surface resiliency of the member which the prothesis is intended to replace. Moreover, the foam material has a sufiicient strength to enable the skeletal structure to undergo rotation at the knee joint under the weight of the user while maintaining stability of the prosthesis. The foam material will cause the prosthesis to return to its initial position upon removal of the force which caused rotation of the joint.

In summary, it is seen that there has been provided a skeletal structure including means comprising an articulated joint which enables the structure to be pivotally moved between extended and collapsed positions. Moreover, there is provided elastic cover means surrounding and accommodating the skeletal structure for urging the structure to assume the extended position thereof while resisting movement of the structure from the extended to the collapsed position. Moreover, the elastic cover means has an outer contour substantially corresponding to the outline of the limb which is being replaced whereas the cover means has a density to provide a surface resilience substantially equal to that of the limb being replaced.

Numerous modifications and variations of the disclosed embodiments will become apparent to those skilled in the art without deviating from the invention as defined in the attached claims.

What is claimed is:

1. An artificial leg comprising a structural arrangement constituted by an elongate foot plate having a lower concave surface, said foot plate having a threaded rearwardly located opening which faces upwardly, a cup member threadably engaged in said foot plate, said cup member having a smooth upwardly facing hemispherical concavity therein, a rod assembly including a spherical end portion accommodated in said concavity for free movement, a cap member encircling said rod assembly and threadably engaged with said cup member, said cap member having an oval hole through which passes said rod assembly and by virtue of which said rod assembly is limited in movement in a front-to-rear direction and in a lateral direction, said oval hole having its greatest dimension arranged in the front-to-rear direction, means including a knee joint comprising two symmetrical elements joined in face-to-face relation and secured to the rod assembly, the latter said elements including a pair of lugs in which are provided aligned holes, said lugs being spaced laterally and defining a space therebetween, and a T-shaped member including a cylindrical portion rotatably engaged in the holes of the lugs of the symmetrical elements and an upwardly projecting portion, said elements and T-shaped member providing relative angular movement about an axis passing centrally through the cylindrical portion of the T-shaped member engaged in the holes of the lugs of the elements, means secured to the T-shaped member for installing the artificial leg onto the stump of an amputee, and means for locking the knee joint in a plurality of relative angular positions between the T-shaped member and the symmetrical elements, the latter means comprising a spring loaded normally retractable pin axially suppoited for sliding movement within the upwardly projecting portion of the T- shaped member for extending therefrom into the space between said lugs, and means in said symmetrical elements defining a plurality of openings in which the retractable pin may be selectively engaged for locking the knee joint in a corresponding relative angular position, the leg further comprising elastic cover means surrounding and accommodating the structural arrangement and exerting resilient force on said arrangement to urge said elements and the T-shaped member of the knee joint to an initial position in which the T-shaped member and said rod assembly are in substantial alignment such that said leg is substantially straight and extended.

2. A leg as claimed in claim 1 wherein said elastic cover means is constituted of a mass of polyurethane foam material and a latex cover layer on said mass.

3. A leg as claimed in claim 1 wherein said elastic cover means is constituted of a mass of foam rubber and a latex cover layer on said mass.

4. An artificial leg comprising a structural arrangement constituted by an elongate foot plate, a cup member secured to said foot plate, said cup member having a smooth upwardly facing hemispherical concavity therein, a rod assembly including a spherical end portion accommodated in said concavity for free movement, a cap member encircling said rod assembly and engaged with said cup member, said cap member having an oval hole through which passes said rod assembly and by virtue of which said rod assembly is limited inmovement in a front-to-rear direction and a lateral direction, said oval hole having its greatest dimension arranged in the front-to-rear direction, means including a knee joint comprising two symmetrical elements joined in face-to-face relation and secured to the rod assembly, the latter said elements including a pair of lugs in which are provided aligned holes, said lugs being spaced laterally and defining a space therebetween, and a T-shaped member including a cylindrical portion rotatably engaged in the holes of the lugs of the symmetrical elements and an upwardly projecting portion, said elements and T-shaped member providing relative angular movement about an axis passing centrally through the cylindrical portion of the T-shaped member engaged in the holes of the lugs 0f the elements, and means secured to the T-shaped member for installing the artificial leg onto the stump of an amputee, the leg further comprising elastic cover means surrounding and accommodating the structural arrangement and exerting resilient force on said arrangement to urge said elements and the T-shaped member of the knee joint to an initial position in which the T-shaped member and said rod assembly are in substantial alignment such that said leg is substantially straight and extended.

5. An artificial leg comprising a structural arrangement including a rod assembly, a knee joint comprising two symmetrical elements joined in face-to-face relation and secured to the rod assembly, the latter said elements including a pair of lugs in which are provided aligned holes, said lugs being spaced laterally and defining a space therebetween, and a T-shaped member including a cylindrical portion rotatably engaged in the holes of the lugs of the symmetrical elements and an upwardly projecting portion, said elements and T-shaped member providing relative angular movement about an axis passing centrally through the cylindrical portion of the T-shaped member engaged in the holes of the lugs of the elements, means secured to the T-shaped member for installing the artificial leg onto the stump of an amputee, and means for locking the knee joint in a plurality of relative angular positions between the T-shaped member and the symmetrical elements, the latter means comprising a spring loaded normally retracted pin axially supported within the upwardly projecting portion of the T-shaped member, means for releasing said pin for extending from the T- shaped member into the space between said lugs, and means in said symmetrical elements defining a plurality of openings in which the pin may be selectively engaged when released for locking the knee joint in a corresponding relative angular position, the leg further comprising elastic cover means surrounding and accommodating the structural arrangement and exerting resilient force on said arrangement to urge said elements and the T-shaped member of the knee joint to an initial position in which the structural arrangement is substantially straight and extended.

6. A structural arrangement for an artificial leg comprising an elongate foot plate, said plate having a threaded rearwardly located opening, a cup member threadably engaged in said foot plate, said cup member having a smooth upwardly facing hemispherical concavity therein, a rod assembly including a spherical end portion, said spherical end portion being accommodated in said concavity for free movement, a cap member encircling said rod assembly and threadably engaged with said cup member, said cap member having an oval hole through which passes said rod assembly and by virtue of which said rod assembly is limited in movement in a front-to-rear direction and a lateral direction, said oval hole having its greatest dimension arranged in the front-to-rear direction, means including a knee joint comprising two symmetrical elements joined in face-to-face relation and secured to the rod assembly, the latter said elements including a pair of lugs in which are provided aligned holes, said lugs being spaced laterally and defining a space therebetween, and a T-shaped member including a cylindrical portion rotatably engaged in the holes of the lugs of the symmetrical elements and an upwardly projecting portion, said elements and T-shaped member providing relative angular movement about an axis passing centrally through the cylindrical portion of the T-shaped member engaged in the holes of the lugs of the elements, means secured to the T-shaped member for installing the artificial leg onto the stump of an amputee, and means for locking the knee joint in a plurality of relative angular positions between the T-shaped member and the symmetrical elements, the latter means comprising a spring loaded retractable pin axially supported within the upwardly projecting portion of the T-shaped member, and extending therefrom into the space between said lugs, and means in said symmetrical elements defining a plurality of openings in which the retractable pin may be selectively engaged for locking the knee joint in the corresponding relative angular position.

7. A knee joint for an artificial leg comprising two symmetrical elements joined in face-to-face relation and including a pair of lugs in which are provided aligned holes, said lugs having a lateral spacing to define a space therebetween, a member including a cylindrical portion rotatably engaged in the holes of the lugs of the symmetrical elements to provide relative angular movement between the member and the symmetrical elements about an axis passing centrally through said cylindrical portion, and means supported in said member for locking the knee joint in a plurality of relative angular positions between the member and the symmetrical elements, said member including a portion projecting from said cylindrical portion between said lugs to define a T-shape for said member, said means for locking the knee joint comprising a spring loaded retractable pin axially supported within the projecting portion of the T-shape member and extending therefrom into the space between the lugs, and means in said symmetrical elements defining a plurality of openings in which the retractable pin may be selectively engaged for locking the knee joint in the corresponding relative angular position.

8. A knee joint as claimed in claim 7 wherein said means defining the plurality of openings comprises a sector element, said symmetrical elements being provided with cavities which cooperatively define a space in which said sector element is secured, said sector element having an inner surface which faces into the space between the References Cited UNITED STATES PATENTS 5 Shepard 329 Ingram 3-32 XR Dickson 3-21 XR Tenenbaum et a1. 312 XR Taylor et a1. 3-12.3 10

RICHARD A. GAUDET, Primary Examiner.

FOREIGN PATENTS R. L. FRINKS, Assistant Examiner. 

